Systems and Methods for Apportioning Usage of a Utility in a Multi-Unit Building

ABSTRACT

Usage of a utility in a multi-unit building is apportioned to a single unit by measuring the total usage of the utility using a meter unit to produce a total usage measurement, then positioning at least one sensor unit in a single unit of the multi-unit building and monitoring usage of the utility by the single unit using the at least one sensor unit to produce monitoring data. Then a processor unit receives the total usage measurement and the monitoring data and correlates them to generate correlated data. Finally, the processor unit apportions the total usage measurement to the single unit based on the correlated data.

FIELD

Embodiments described herein relate to systems and methods forapportioning usage of a utility in a multi-unit building. Moreparticularly, embodiments described herein relate to systems and methodsfor apportioning usage of a utility in a multi-unit building bymonitoring usage in each unit and correlating the monitoring data withthe total multi-unit building usage.

BACKGROUND

It is often inconvenient to individually meter utility usage in amulti-unit building such as an apartment building or a condominium. Inmany multi-unit buildings the main utility supply line is metered forthe building as a whole. Usage is then arbitrarily apportioned to theunits (e.g. by unit size or number of occupants) since individualmetering is not provided for each unit. For example, in the case ofwater installations, it is typical for older buildings to employvertical feed lines, with a single line supplying a plurality ofvertically aligned water fixtures (e.g. sinks and toilets) acrossmultiple units. In this case, each unit may have multiple pairs ofsupply lines feeding the various water fixtures in the unit, and eachsupply line may feed water fixtures in many units. Accordingly, it maybe difficult and inconvenient to meter each unit individually.

SUMMARY

The embodiments described herein provide in one aspect, a method forapportioning usage of a utility in a multi-unit building. The methodincludes (a) measuring the total usage of the utility by the multi-unitbuilding using a meter unit to produce a total usage measurement; (b)positioning at least one sensor unit in a single unit of the multi-unitbuilding; (c) monitoring usage of the utility by the single unit usingthe at least one sensor unit to produce monitoring data; (d) receivingthe total usage measurement and the monitoring data at a processor unit;(e) correlating the total usage measurement and the monitoring datausing the processor unit to generate correlated data; and (f)apportioning the total usage measurement to the single unit using theprocessor unit based on the correlated data.

The embodiments described herein provide in another aspect a system forapportioning utility usage in a multi-unit building. The system includes(a) a meter unit mounted to a main feed pipe for measuring the usage ofthe utility by the multi-unit building to generate a total usagemeasurement, the main feed pipe supplying the utility to the multi-unitbuilding; (b) at least one sensor unit positioned in a single unit ofthe multi-unit building for monitoring use of the utility by the singleunit to generate monitoring data; and (c) a processor unit. Theprocessor unit then receives the total usage measurement from the meterunit, receives the monitoring data from the at least one sensor unit,correlates the total usage measurement and the monitoring data togenerate correlated data, and then apportions the total usagemeasurement to the single unit based on the correlated data.

Further aspects and advantages of the embodiments described herein willappear from the following description taken together with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of embodiments of the systems and methodsdescribed herein, and to show more clearly how they may be carried intoeffect, reference will be made, by way of example, to the accompanyingdrawings in which:

FIG. 1 is a schematic diagram of a system for apportioning water usageto single units of a multi-unit building;

FIG. 2 is a flowchart of a method of apportioning water usage to singleunits of a multi-unit building using the system of FIG. 1 in accordancewith at least one embodiment;

FIG. 3 is a flowchart of a method for assigning usage to each singleunit based on the correlated data in accordance with at least oneembodiment;

FIG. 4 is a graph of exemplary building usage measurement and monitoringdata from non-invasive sensor units;

FIG. 5 is a graph of exemplary building usage measurement and monitoringdata from non-invasive sensor units; and

FIG. 6 is a graph of another exemplary building usage measurement andmonitoring data from non-invasive sensor units.

It will be appreciated that for simplicity and clarity of illustration,elements shown in the figures have not necessarily been drawn to scale.For example, the dimensions of some of the elements may be exaggeratedrelative to other elements for clarity. Further, where consideredappropriate, reference numerals may be repeated among the figures toindicate corresponding or analogous elements.

DETAILED DESCRIPTION

It will be appreciated that numerous specific details are set forth inorder to provide a thorough understanding of the exemplary embodimentsdescribed herein. However, it will be understood by those of ordinaryskill in the art that the embodiments described herein may be practicedwithout these specific details. In other instances, well-known methods,procedures, and components have not been described in detail so as notto obscure the embodiments described herein. Furthermore, thisdescription is not to be considered as limiting the scope of theembodiments described herein in any way but rather as merely describingthe implementation of the various embodiments described herein.

Embodiments described herein relate to systems and methods forapportioning usage of a utility in a multi-unit building wherein asensor unit is installed on one or more unit feed pipes and themeasurements taken by the sensors units are time correlated with themeasurement taken on the main feed pipe to determine the usageattributable to each unit.

The system and methods will be described in relation to apportioningwater usage; however, it will be evident to a person of skill in the artthat the systems and methods described herein may be used to measureusage or flow of any fluid where applicable.

Reference is now made to FIG. 1, which illustrates a system 100 forapportioning water usage in a multi-unit building 102. The term“multi-unit building” will be used herein to describe any residential,commercial, or industrial building, such as an apartment building, acondominium, or an office building, having a plurality of units. Itshould be understood that while the multi-unit building 102 is onlyshown in FIG. 1 to have first and second single units 104, 106, themulti-unit building 102 may have any number of units.

In some embodiments, the system 100 may be used to apportion water usagein a single-unit building such as a house. In these embodiments, thesystem 100 may be used to determine water usage made by specificappliances (e.g. dish washers, washing machines etc.) andwater-consuming fixtures (e.g. toilets, sinks). Further, the system 100may be used to facilitate a pay-per-use system for such appliances andwater-consuming fixtures, whereby the system 100 may determine thequantity of water used with each use of the appliance or water-consumingfixture.

Water is supplied to the multi-unit building 102 from the water suppliervia a main feed pipe 108. The main feed pipe 108 supplies water to themulti-unit building's cold water feed pipe 110 and hot water feed pipe112.

Water entering the multi-unit building 102 via the main feed pipe 108 istypically cold and requires heating before it enters the hot water feedpipe 112. It will be appreciated that water which supplies the hot waterfeed pipe 112 may be heated by any means known in the art. For example,in the embodiment of FIG. 1, water in the hot water feed pipe 112 isfirst heated by a hot water heater 111.

Each single unit 104, 106 of the multi-unit building 102 comprises oneor more water outlets 120. A water outlet may be any fixture, applianceor otherwise that consumes water. For example, dishwashers, washingmachines, sinks, showers, toilets and some refrigerators are wateroutlets in the sense that they consume water supplied by one or both ofthe cold and hot water feed pipes 110, 112. In the embodiment shown inFIG. 1, each single unit 104, 106 comprises four exemplary water outlets120: a kitchen sink, a tub and/or shower, a toilet, and a bathroom sink.

It will be appreciated that there may be any number of cold and hotwater feed pipes 110, 112 in a multi-unit building 102. For example, amulti-unit building 102 may have two pairs of cold and hot water feedpipes 110, 112 (second pair not shown). In this example, the first pairof cold and hot water feed pipes 110, 112 may extend vertically throughthe kitchens of a plurality of vertically aligned single units 104, 106.Also, the second pair of cold and hot water feed pipes (not shown) mayextend vertically through bathrooms of a plurality of vertically alignedsingle units 104, 106.

Each of the water outlets 120 receives water from one or more cold andhot water unit feed pipes 130, 140. Cold water unit feed pipes 130connect to and receive water from the cold water feed pipe 110, and thecold water unit feed pipes 130 supply cold water to a correspondingwater outlet 120. Hot water unit feed pipes 140 connect to and receivewater from the hot water feed pipe 112, and the hot water unit feedpipes 140 supply hot water to a corresponding water outlet 120. Forexample, in the embodiment shown in FIG. 1, each kitchen sink receiveswater from both a cold water unit feed pipe 130 and a hot water unitfeed pipe 140, while each toilet only receives water from a cold waterunit feed pipe 130.

A meter unit 150 attached to the main feed pipe 108 measures thequantity of water supplied to the multi-unit building 102 via the mainfeed pipe 108. The main feed pipe meter unit 150 may be one of avolumetric meter, a flow meter or any other type of measuring equipmentsuitable for measuring fluid consumption. The water supplier uses thereadout provided by the main feed pipe meter unit 150 to calculate autility bill for the owner of the multi-unit building 102.

In a typical water supply system, the main feed pipe meter unit 150 isthe only device used by the water supplier to measure the usage of waterby the multi-unit building 102. It is not possible to accuratelydetermine the water consumption by each of the single units 104, 106 ofthe multi-unit building 102 by using only data from the main feed pipemeter unit 150.

To mitigate the shortcomings of a single meter in a multi-unit building,some buildings distribute utility costs amongst tenants according to oneor more of their unit size and their number of occupants. This, however,may be seen as unfair by the tenants, and further does not provide apractical incentive for a unit's tenant to conserve utilities. Forexample, a tenant in a condominium building of 30 equal units would beresponsible for 3% of the utility bill. Accordingly, all things beingequal, if that tenant managed to conserve an additional $30 worth of autility, their share of the utility bill would only drop $1.Apportioning the utility bill based on individual usage affords agreater incentive to conserve utility consumption.

To this end, a non-invasive sensor unit 160 may be installed on at leastone unit feed pipe 130, 140 and/or on the water outlet 120. This way,the non-invasive sensor unit 160 can monitor for water flow through theat least one unit feed pipe 130, 140 and/or water outlet 120 on which itis installed. For example, in some embodiments, where pipes are hiddenin a wall, it may be particularly convenient to spot-weld a non-invasivesensor unit 160 to the body of a water faucet instead of installing anon-invasive sensor unit 160 on a unit feed pipe 130, 140. That is,sensor unit 160 may be installed at least one unit feed pipe 130, 140and water outlet 120; only on at least one unit feed pipe 130, 140; oronly on the water outlet 120, depending on the type and number ofmeasurements desired.

The term “non-invasive” is used herein to refer to non-invasive sensorunits 160 that can be installed on a unit feed pipe 130, 140 or on awater outlet 120 without cutting or otherwise disrupting the unit feedpipe 130, 140 or water outlet 120. In contrast, the retrofitting of amulti-unit building with utility meters as typically used today requirescutting a pipe twice, threading the pipe, attaching the conventionalsensor, and making sure that the joints are not leaking. This is aninvasive, laborious and expensive operation that can be avoided usingnon-invasive sensor units 160.

It is not a requirement of the sensor units 160 to measure quantity offlow or volume, rather, the non-invasive sensor units 160 monitor theunit feed pipes 130, 140 or water outlet 120 to detect whether or notthere is water flowing through them. For example, each non-invasivesensor unit 160 may at least monitor their respective unit feed pipe130, 140 and/or water outlet 120 to detect the times at which waterstarts and stops flowing through their respective unit feed pipe 130,140 and/or water outlet 120.

In some embodiments, the non-invasive sensor units 160 may measure achange of water flow through a water outlet 120. For example, thenon-invasive sensor unit 160 may determine that the water flow through awater outlet 120 has changed by a positive or a negative rate, relativeto a previous measurement.

It will be appreciated that the non-invasive sensor units 160 maymonitor for any of a variety of indications of water flow. For example,a non-invasive sensor unit 160 may utilize an acoustic sensor such as amicrophone to determine the start and stop times of fluid flow by usingthe acoustic sensor to detect changes in sound coming from the unit feedpipe 130, 140 and/or water outlet 120. In this example, the non-invasivesensor unit 160 may determine that water begins flowing through a unitfeed pipe 130, 140 and/or water outlet 120 when it detects a minimumrise in sustained sound levels coming from the unit feed pipe 130, 140and/or water outlet 120. Similarly, the non-invasive sensor unit 160 maydetermine that water has stopped flowing when it detects a minimum dropin sustained sound levels coming from the unit feed pipe 130, 140 and/orwater outlet 120.

In another embodiment, the non-invasive sensor unit 160 utilizes anacoustic sensor and monitors for a relative amount of water flow. Inthis case, the non-invasive sensor unit 160 may determine the fractionof the water outlet's maximum consumption rate being consumed bymonitoring the sound pressure and/or spectral distribution of the soundcoming from the unit feed pipe 130, 140 and/or water outlet 120. Thecorrelation between a water outlet's water consumption and the soundpressure and/or spectral distribution coming from the unit feed pipe130, 140 and/or water outlet 120 may be calibrated for each water outlet120.

In another example, a non-invasive sensor unit 160 may utilize atemperature sensor to determine the start and stop times by monitoringfor changes in temperature of the unit feed pipe 130, 140 and/or wateroutlet 120. In this example, the non-invasive sensor unit 160 maydetermine that water is flowing through a cold water unit feed pipe 130and/or water outlet 120 when it registers a minimum drop in temperatureof the cold water unit feed pipe 130 and/or water outlet 120. Similarly,the non-invasive sensor unit 160 may determine that water has stoppedflowing through a cold water unit feed pipe 130 and/or water outlet 120when it registers a subsequent minimum rise in temperature of the coldwater unit feed pipe 130 and/or water outlet 120.

In some embodiments, a water feed pipe meter unit 155 can be used tomeasure the consumption of water through one of the water feed pipes110, 112. The water feed pipe meter unit 155 may be installed on, andmeasure the water consumption of, one of the hot water feed pipes 112(as shown in FIG. 1) or the cold water feed pipe 110 (not shown). Thismay provide for more accurate apportioning of cold and hot water usage.Apportioning cold and hot water consumption separately may besignificant where the cost to heat the water in the hot water feed pipe112 makes hot water usage considerably more expensive than cold waterusage.

Data collected by the non-invasive sensor units 160, the main feed pipemeter unit 150, and the water feed pipe meter unit 155 may becommunicated by a wired or wireless network to a processor unit 186 forapportioning the utility consumption to the first and second singleunits 104, 106.

Reference is now made to FIG. 2 that illustrates a method 200 forapportioning water usage to the single units 104, 106 of the multi-unitbuilding 102 using the system 100 of FIG. 1 in accordance with anembodiment of the present disclosure.

At step 202, the total water usage of the multi-unit building 102 ismeasured using the main feed pipe meter unit 150 to produce a buildingusage measurement and a total water usage measurement. The term“building usage measurement” refers to data reflecting the total amountof water that enters the building via the main feed pipe 108 asregistered by the main feed pipe meter unit 150 over a period of time.In contrast, the term “total water usage measurement” refers to datareflecting the collective water usage to be apportioned to the singleunits 104, 106 of the multi-unit building 102 over a period of time.

In some embodiments, the difference between the building usagemeasurement and the total water usage measurement will be known as basewater usage. Base water usage may be caused by leakage or by waterflowing to a water outlet 120 that is not monitored by a non-invasivesensor unit 160. Base water usage may be constant or may vary over time.In certain embodiments where base water usage varies, base water usagecan be approximated by measuring the base usage directly at the mainmeter 150 at times where no usage is registered in the single units 104,106 and assuming that the base usage varies linearly between thesemeasurements. The approximated base water usage may be used to calculatewater consumption that should not to be attributed to the single units104, 106. Subtracting the base water usage from the building usagemeasurement will produce the total water usage measurement that can thenbe apportioned to the single units 104, 106.

Alternatively, the building usage measurement may not be adjusted forbase water usage and the total usage measurement may be equal to thebuilding usage measurement (i.e. the total amount of water which entersthe building via the main feed pipe 108 as registered by the main feedpipe meter unit 150).

In some variant embodiments, the building usage measurement may comprisea plurality of data points. Each data point may comprise a timestamp anda corresponding water measurement from the main feed pipe meter unit 150(optionally adjusted for base water usage). The water measurement may beexpressed in terms of cumulative volumetric water usage, instantaneouswater flow rate or any other useful measurement. The water usagemeasurement may have sufficient temporal resolution to permit themeasuring unit (e.g. volumetric water usage) to be converted withsufficient accuracy to another measuring unit (e.g. instantaneous waterflow rate).

In some embodiments, the building usage measurement may comprise watermeasurements from both the main feed pipe meter unit 150 and the waterfeed pipe meter unit 155. In these embodiments, the building usagemeasurement may comprise data points that comprise a timestamp and ameasurement from each of the main feed pipe meter unit 150 and the waterfeed pipe meter unit 155, each optionally adjusted for base water usage.

For example, where the water feed pipe meter unit 155 is installed onthe hot water feed pipe 112, the hot water building usage measurementmay be determined directly from the hot water feed pipe meter unit 155and the cold water building usage measurement may be determined as thedifference between the building usage measurement (from the main feedpipe meter unit 150) and the hot water building usage measurement. Oncethe cold and hot water building usage measurements are separatelydetermined, they may be optionally adjusted for cold and hot base waterusage to determine the cold and hot total water usage measurements thatwill be apportioned separately.

Alternatively, where the water feed meter unit 155 is not installed onthe hot water feed pipe 122 and measurements for hot water are notavailable as a separate measurement, other means may be used todetermine the amount of hot water consumed at a single utility point.The individual cold and hot water usage can be determined by registeringthe combined cold and hot water flow at a utility point by anon-invasive sensor unit 160 and further determining the relative amountof cold and hot water at the water outlet 120. The relative amount ofcold and hot water at a water outlet 120 can be determined by a varietyof means. For example, the relative amount of cold and hot water can bedetermined by positioning a non-invasive temperature sensor unit 160 ata point on the water outlet 120 where the temperature is influenced byboth the cold and hot water.

In some embodiments it may suffice to approximately measure the relativeamount of cold and hot water by making the assumption that the relativeamount of hot and cold water flowing through the water outlet 120 isconstant over one instance of usage, and then measuring the temperatureof the mixture at multiple times, then using only one of saidmeasurements, where the temperature is sufficiently stable over time. Invariant embodiments, more advanced calculations may be performed on suchmeasurements to gain better precision, using for example known orassumed diffusion profiles of the heat transfer for the water outlet 120combined with the measured start and stop times of usage of water at thewater outlet 120.

In another embodiment, the relative amount of cold and hot water willnot be constant over time and measuring the temperature of the mixtureat multiple times may be used as an approximation of the relative flowof cold and hot water over time. These measurements may again besubjected to more advanced calculations as described to betterapproximate the true relative amount of hot and cold water beingconsumed. In variant embodiments, the temperature of the cold and hotwater before entering the water outlet 120 and being mixed may bemeasured to further facilitate calculations of the relative amount ofcold and hot water being consumed.

In another embodiment the cold water temperature is assumed to beconstant at the point where it is being supplied to the water outlet 120by the unit feed pipe 130, and the hot water temperature is assumed tobe constant at the point where it is being supplied to the water outlet120 by the unit feed pipe 140.

The method that the above measurements are made, calculated, andinterpreted, is largely a matter of what is considered to be “fair”. Forexample, in one embodiment, a tenant opening a hot water tap on a faucetwill pay the cold water price for the water when the water that comesout of the water outlet 120 is cold, and the hot water price when thewater coming out of the water outlet 120 is hot. In certain embodiments,especially in older multi-unit buildings, it will take a differentamount of time for hot water temperature to stabilize in differentunits. Once the total water usage measurement has been determined, themethod 200 proceeds to step 204.

At step 204, at least one non-invasive sensor unit 160 is positioned inat least one single unit 104, 106 of the multi-unit building 102. Asdescribed above, typically one non-invasive sensor unit 160 is installedon each unit feed pipe 130, 140 and/or water outlet 120 of each singleunit 104, 106. As previously discussed, sensor unit 160 may be installedon at least one unit feed pipes 130, 140 and/or water outlet 120; onlyon at least one unit feed pipes 130, 140; or only on the water outlet120, depending on the type and number of measurements desired. Once thenon-invasive sensor units 160 have been installed in the first andsecond single units 104, 106, the method 200 proceeds to step 206.

At step 206, the non-invasive sensor units 160 are used to monitor theusage of water by the single units 104, 106 and to produce monitoringdata. In some embodiments each non-invasive sensor unit 160 monitorstheir respective unit feed pipe 130, 140 to detect the times at whichwater starts and stops flowing through their respective unit feed pipe130, 140. In certain embodiments, the cold and hot water is mixed in thewater outlet 120, and a combination of non-invasive sensor units 160 areemployed to measure the start times of cold and hot water, andapproximately measure the relative amount of cold and hot water beingconsumed. In certain embodiments, the non-invasive sensor units 160additionally measure changes in the water flow, to allow for attributionof changes in consumption, in the event that more than one water outlet120 is consuming water.

As described above, the non-invasive sensor units 160 may be configuredto monitor for any of a variety of indications of water flow. It willalso be appreciated that the non-invasive sensor units 160 may monitorfor a plurality of indications (e.g. temperature and sound) to producemore accurate monitoring data (e.g. more accurate water flow start andstop times, or more accurately determine a change in flow through thewater outlet 120). Once the monitoring data has been produced, themethod 200 proceeds to step 208.

At step 208, the total usage measurement generated by the main feed pipemeter unit 150 (and the hot water feed pipe meter unit 155 ifimplemented) and the monitoring data generated by the non-invasivesensor units 160 are received at the processor unit 186. The total usagemeasurement and the monitoring data may be transmitted from the mainfeed pipe meter unit 150 (and the hot water feed pipe meter unit 155 ifimplemented) and the non-invasive sensor units 160 respectively via awired or wireless network.

In one embodiment, the processor unit 186 is integrated with any one ofthe devices of the system. For example, in one embodiment the processorunit 186 is integrated with the main feed pipe meter unit 150. In atleast one alternative embodiment the processor unit 186 is a remoteprocessor unit and exists as a physically separate entity from themulti-unit building 102.

In one embodiment, the non-invasive sensor units 160 form a wirelessmesh network. In this embodiment, the monitoring data can be relayed tothe processor unit 186 via a series of non-invasive sensor units 160.For example, the non-invasive sensor units 160 may be able to receivemonitoring data from neighboring non-invasive sensor units 160 andretransmit this data to the processor unit 186 or an intermediarynon-invasive sensor unit 160 if the processor unit 186 is out of range.Once the total usage measurement and the monitoring data have beentransmitted to the processor unit 186, the method 200 proceeds to step210.

At step 210, the total usage measurement and the monitoring data arecorrelated using the processor unit 186 to generate correlated data. Thetotal usage measurements of start and stop times are correlated with themeasurements of flow or quantity to produce measurements of individualconsumption. It will be appreciated that correlated data may take anyform suitable for apportioning the utility usage to the first and secondsingle units 104, 106. For example, where the monitoring data comprisesstart and stop times of water flow at each unit feed pipe 130, 140and/or water outlet 120, the correlated data may comprise data of everystart and stop time alongside the total usage measurement correspondingto those start and stop times. In this example, the total usagemeasurement for any given start or stop time may be read from thecorrelated data.

In a particular embodiment, the processor unit 186 is configured topresent the data in various forms, including providing a display oruser-interface (not shown) on the main feed pipe meter unit 150 foroutputting the data. In a further embodiment, the data can be madeavailable to the Internet via a GSM network for presentation in the formof a webpage.

Once the total usage measurement and the monitoring data are correlatedusing the processor unit 186, the method 200 proceeds to step 212.

At step 212, the total usage measurement is apportioned to the first andsecond single units 104, 106 using the processor unit 186 based on thecorrelated data. Apportioning the total usage measurement to the firstand second single units 104, 106 assigns a volume of consumed water toeach single unit 104, 106. An exemplary method for assigning usage toeach single unit 104, 106 based on the correlated data is described inrelation to FIG. 3. Once the total usage measurement has beenapportioned, the first and second single units 104, 106 can beappropriately charged for the amount of water that they actuallyconsumed.

Reference is now made to FIG. 3, which illustrates an exemplary method300 for assigning usage to the first and second single units 104, 106 ofthe multi-unit building 102 based on the correlated data in accordancewith an embodiment of the present disclosure. The method 300 determineshow much water consumption to assign to the first and second singleunits 104, 106 for a time period of interest. For the purposes of thisexample, the time period of interest is defined as the time between apair of sequential start and stop times from a non-invasive sensor unit160 which is installed on a unit feed pipe 130 in the first single unit104. For clarity, this exemplary method assumes (i) that each singleunit 104, 106 only has one unit feed pipe 130; (ii) that the monitoringdata includes water flow start and stop times for each unit feed pipe130, 140; and (iii) that the correlated data includes the start and stoptimes time correlated with the total usage measurement.

At step 302, it is determined whether water is only flowing through theunit feed pipe 130 of the first single unit 104, as opposed to bothsingle units 104, 106, during the time period of interest. This can bedetermined, for example, by assessing whether any time periods betweensequential start and stop times from the non-invasive sensor unit 160 ofthe second single unit 106 overlap with the time period of interest. Ifthere is no such overlap, then water is only flowing through the unitfeed pipe 130 of the first single unit 104 during the time period ofinterest. In that case, the method 300 proceeds to step 304. If on theother hand there is overlap, then water is flowing through the unit feedpipes 130 of both the first and second single units 104, 106 during thetime period of interest, and the method 300 proceeds to step 306.

At step 304, if water is only flowing to the first single unit 104during the time period of interest then all of the water consumed by themulti-unit building 102, (optionally adjusted for base water usage),during the time period of interest is attributed to the first singleunit 104. Accordingly, the total usage measurement for the time periodof interest is assigned to the first single unit 104.

At step 306, if water is flowing to both the first and second singleunits 104, 106 during the time period of interest then it is determinedwhether the water flow start and stop times of the two unit feed pipes130 are both identical. If the start and stop times of the two unit feedpipes 130 are not both identical then the water is flowing through thetwo unit feed pipes 130 during overlapping but not identical timeperiods and the method 300 proceeds to step 308. If the start and stoptimes of the two unit feed pipes 130 are identical then the water isflowing through the two unit feed pipes 130 during the exact same periodof time and the method 300 proceeds to step 310.

At step 308, the water flow start and stop times for the two unit feedpipes 130 are not both identical. Accordingly, a portion of the totalusage measurement for the time period of interest is assigned to each ofthe two single units 104, 106 based on the difference in the total usagemeasurement between one of the start times and the stop times. Thisconcept will be explained with reference to FIG. 4.

FIG. 4 shows an exemplary graph of building usage measurement data andmonitoring data from non-invasive sensor units 160. The building usagemeasurement on this graph is represented by flow rate. The non-invasivesensor unit 160 on the unit feed pipe 130 of the first single unit 104registers a water start time of t_(a) and a subsequent stop time oft_(c). Similarly, the non-invasive sensor unit 160 on the unit feed pipe130 of the second single unit 106 registers a start time of t_(b) and asubsequent stop time of t_(c). Further the main feed pipe meter unit 150registers a rise in flow rate from W to X at t_(a), from X to Y att_(b), and from Y to W at t_(c).

In this example, the total usage measurement will be adjusted for basewater usage. Prior to time t_(a) and after time t_(c) the non-invasivesensor units 160 are not registering any flow through the unit feedpipes 130 of the single units 104, 106. Accordingly, the flow prior tot_(a) and after t_(c) is flow which is unattributable to the singleunits 104, 106 and therefore is flow from base water usage (“base waterflow”). Although the base water flow may actually vary between timet_(a) and time t_(c), it may be assumed that the flow varies linearly.Therefore, because in this example prior to time t_(a) and after timet_(c) the base water flow is W, it may be assumed that the base waterflow is constant at W throughout the time period of interest (from t_(a)to t_(c)).

Persons skilled in the art will understand that the total usagemeasurement may be determined from this graph of building usagemeasurement by subtracting the base water flow (i.e. W) from each datapoint. If it is assumed that the pattern of water consumption for agiven unit feed pipe 130 is that it rises from zero to a constant thenback to zero again then the water consumption attributable to the firstsingle unit 104 is approximately a flow rate of (X-W) for a time periodof (t_(c)-t_(a)). Similarly, the water consumption of the second singleunit 106 may be approximated by the difference in the total usagemeasurement at the start times t_(a) and t_(b) (i.e. a flow rate of(Y-X)) for a time period of (t_(c)-t_(b)).

FIG. 5 shows a second exemplary graph of building usage measurement dataand monitoring data from non-invasive sensor units 160. FIG. 5 presentsthe same data as FIG. 4 except that at time t_(c) the main feed pipemeter unit 150 registers a water consumption of zero. In this example,prior to t_(a) there is a base water flow of W and after t_(c) there isa base water flow of zero. Therefore, using a linear approximation, thebase water flow may be assumed to vary linearly from W to zero duringthe time period of interest (from t_(a) to t_(c)). Therefore, the waterconsumption attributable to base water usage may be equal to the timeintegration of the base water flow over the time period of t_(a) tot_(c) (hatched). Accordingly, the water consumption that is attributableto the first single unit 104 is approximately a flow rate of (X-W) for atime period of (t_(c)-t_(a)) less the base water usage during the timeperiod from t_(a) to t_(c). Similarly, the water consumption that isattributable to the second single unit 106 is approximately a flow rateof (Y-X) for a time period of (t_(c)-t_(b)) less the base water usageduring the time period from t_(b) to t_(c).

FIG. 6 shows a third exemplary graph of building usage measurement dataand monitoring data from non-invasive sensor units 160. FIG. 6 presentsthe same data as FIG. 4 except that the main feed pipe meter unit 150registers an increase in flow rate from X to V at t_(d). This exemplarygraph illustrates a situation where there is a simultaneous stop timeand the flow is changed at one unit after the start time. To determinein which single unit 104, 106 the change in flow through the unit feedpipe 130 occurred the non-invasive sensor unit 160 measures a change inflow at the unit feed pipe 130 which experiences the increase in flow.The single unit 104, 106 that experiences the flow increase would havethat utility use attributed to them. Without this determination, thechange in flow rate could be attributable to either single unit 104,106. The same method can be used where there is a simultaneous starttime and the main feed pipe meter unit 150 registers a decrease in flowrate to determine which single unit 104, 106 to attribute the use to.

It will be appreciated that although FIGS. 4, 5, and 6 show exampleswhere the start times are different and the stop times are the same, itis contemplated that utility consumption may be apportioned to aplurality of single units 104, 106 with any variation of relative startand stop times. For example, the start and stop times may all bedifferent or they may be all the same. As explained above, if the starttimes are all the same and the stop times are all the same the methodproceeds to step 310.

At step 310, if the water flow start and stop times of the unit feedpipes 130 of each of the single units 104, 106 are identical then aportion of the total usage measurement is assigned to each of the singleunits 104, 106 based on other factors. It will be appreciated that anysuitable factors may be considered to apportion the water consumptionbetween the two single units 104, 106.

For example, a portion of the total usage measurement may be assigned toeach of the single units 104, 106 based on historic consumption of theutility by each of the first and second single units 104, 106. In thisexample, if historically the first single unit 104 consumes twice asmuch water as the second single unit 106, then ⅔ of the total usagemeasurement may be assigned to the first single unit 104 and ⅓ of thetotal usage measurement may be assigned to the second single unit 106.

In another example, a portion of the total usage measurement may beassigned to each of the single units 104, 106 based on historicconsumption rate of the utility by the unit feed pipes 130 of each ofthe single units 104, 106. In this example, if historically the wateroutlet 120 of the first single unit 104 consumes water twice as fast asthe water outlet 120 of the second single unit 106, then ⅔ of the totalusage measurement may be assigned to the first single unit 104 and ⅓ ofthe total usage measurement may be assigned to the second single unit106. In still another example, an equal portion of the total usagemeasurement may be assigned to each of the first and second single units104, 106.

While the method 300 has been described in reference to a multi-unitbuilding 102 with two single units 104, 106 where each single unit 104,106 only has as single unit feed pipe 130, it will be evident to aperson of skill in the art that the method 300 can be extrapolated toencompass any number of units with any number of unit feed pipes.

For example, where the multi-unit building 102 has two single units 104,106 and each single unit 104, 106 has both a cold water unit feed pipe130 and a hot water unit feed pipe 140, the hot water consumption andthe cold water consumption may be apportioned to each single unit 104,106 separately. In this embodiment, the total usage measurement maycomprise the multi-unit building's hot water consumption and cold waterconsumption determined by using both the main feed pipe meter unit 150and a water feed pipe meter unit 155, as described above. Alternatively,the mixture of cold and hot water can be determined using the method asdescribed earlier (measuring the relative flow of cold and hot water todetermine the proportion of cold and hot water used).

While the above description provides examples of the embodiments, itwill be appreciated that some features and/or functions of the describedembodiments are susceptible to modification without departing from thespirit and principles of operation of the described embodiments.Accordingly, what has been described above has been intended to beillustrative of the invention and non-limiting and it will be understoodby persons skilled in the art that other variants and modifications maybe made without departing from the scope of the invention as defined inthe claims appended hereto.

1. A method for apportioning usage of a utility in a multi-unitbuilding, the method comprising: (a) measuring total usage of theutility by the multi-unit building using a meter unit to produce a totalusage measurement; (b) positioning at least one sensor unit in a singleunit of the multi-unit building; (c) monitoring usage of the utility bythe single unit using the at least one sensor unit to produce monitoringdata; (d) receiving the total usage measurement and the monitoring dataat a processor unit; (e) correlating the total usage measurement and themonitoring data using the processor unit to generate correlated data;and (f) apportioning the total usage measurement to the single unitusing the processor unit based on the correlated data.
 2. The method ofclaim 1 wherein monitoring usage of the utility by the single unitcomprises: (i) determining a start time for usage of the utility; and(ii) determining a stop time for usage of the utility.
 3. The method ofclaim 2, wherein determining the start and stop times comprisesmonitoring the sound in at least one of a unit feed pipe and a utilityoutlet.
 4. The method of claim 2, wherein determining the start and stoptimes comprises monitoring the temperature of at least one of a unitfeed pipe and a utility outlet.
 5. The method of claim 2, furthercomprising: (i) positioning at least one sensor unit in each of aplurality of single units of the multi-unit building; (ii) monitoringusage of the utility by each of the plurality of single units using thesensor units to produce monitoring data; and (iii) apportioning thetotal usage measurement to the plurality of single units using theprocessor unit based on the correlated data.
 6. The method of claim 4,wherein apportioning the total usage measurement to the plurality ofsingle units comprises: (i) if the start and stop times of a particularsingle unit are unique to the particular single unit, assigning thetotal usage measurement to the particular single unit; (ii) if the timeperiod between start and stops times for at least two single unitsoverlap, but are not identical, assigning a portion of the total usagemeasurement to each of the at least two single units based on thedifference in the total usage measurement between one of the start timesand the stop times; and (iii) if the start and stop times of at leasttwo single units are identical, assigning a portion of the total usagemeasurement to each of the at least two single units based on historicusage of the utility by each of the at least two single units.
 7. Themethod of claim 1, wherein measuring the total usage of the utility bythe multi-unit building comprises measuring one of flow and quantity ofthe utility through the main feed pipe.
 8. The method of claim 1,wherein the method further comprises wirelessly transmitting the totalusage measurement from the meter unit to the processor unit.
 9. Themethod of claim 1, wherein the method further comprises wirelesslytransmitting the monitoring data from the at least one sensor unit tothe processor unit.
 10. A system for apportioning utility usage in amulti-unit building, the system comprising: (a) a meter unit mounted toa main feed pipe for measuring the usage of the utility by themulti-unit building to generate a total usage measurement, the main feedpipe supplying the utility to the multi-unit building; (b) at least onesensor unit positioned in a single unit of the multi-unit building formonitoring use of the utility by the single unit to generate monitoringdata; (c) a processor unit for: receiving the total usage measurementfrom the meter unit; receiving the monitoring data from the at least onesensor unit; correlating the total usage measurement and the monitoringdata to generate correlated data; and apportioning the total usagemeasurement to the single unit based on the correlated data.
 11. Thesystem of claim 10 wherein the at least one sensor unit is configuredto: (i) determine a start time for usage of the utility; and (ii)determine a stop time for usage of the utility.
 12. The system of claim11, wherein the at least one sensor unit comprises an acoustic sensorfor determining the start and stop times based on sound detected in atleast one of the unit feed pipe and the utility outlet.
 13. The systemof claim 11, wherein the at least one sensor unit comprises atemperature sensor for determining the start and stop times based on thetemperature in at least one of one of the unit feed pipe and the utilityoutlet.
 14. The system of claim 10, wherein the meter unit measures oneof flow and quantity of the utility through the main feed pipe.
 15. Thesystem of claim 10, further comprising: at least one sensor unitpositioned in each of a plurality of single units of the multi-unitbuilding for monitoring usage of the utility by each single unit togenerate monitoring data; and wherein the processor unit is furtherconfigured for apportioning the total usage measurement to the pluralityof single units based on the correlated data.
 16. The system of claim15, wherein apportioning the total usage measurement to the plurality ofsingle units comprises: (i) if the start and stop times of a particularsingle unit are unique to a particular unit, assigning the total usagemeasurement to the particular single unit; (ii) if the time periodbetween start and stops times for at least two single units overlap, butare not identical, assigning a portion of the total usage measurement toeach of the at least two single units based on the difference in totalusage measurement between one of the start times and the stop times; and(iii) if the start and stop time of at least two single units areidentical, assigning a portion of the total usage measurement to each ofthe at least two single units based on historic usage of the utility byeach of the at least two single units.
 17. The system of claim 10,wherein the meter unit comprises a wireless transmission unit forwirelessly transmitting the total usage measurement to the processorunit.
 18. The system of claim 17, wherein the at least one sensor unitcomprises a wireless transmission unit for wirelessly transmitting themonitoring data to the processor unit.
 19. The system of claim 18,wherein the meter unit, the at least one sensor unit and the processorunit form a wireless mesh network.